More than 11,000 scientists have declared a ‚climate emergency.‘ One of the best things we can do, they say, is have fewer children.

Melting ice shows through at a cliff face at Landsend, on the coast of Cape Denison in Antarctica January 2, 2010. Antarctica pact partners have set up a new protected geological site on the frozen continent to preserve rare minerals that could shine a spotlight on the region\'s history and evolution over millions of years. At a meeting in Brazil in May 2014, the signatories to the Antarctic Treaty designated the Larsemann Hills region of the continent as an Antarctic Specially Protected Area. Picture taken January 2, 2010.Pauline Askin/Reuters

A group of more than 11,250 scientists from around the world have signed a declaration stating that our planet is in the midst of a „climate emergency.“

More than 11,250 scientists from 153 countries have co-signed a warning declaring „clearly and unequivocally that planet Earth is facing a climate emergency.“

Without deep and lasting shifts in the human activities that contribute to climate change, they wrote, „untold human suffering“ is unavoidable.

The authors published the warning Tuesday in the journal BioScience, and it’s based off an analysis of 40 years of data about rising greenhouse-gas emissions, warming oceans, and melting Arctic and Antarctic ice. The coalition of scientists said they have a moral obligation to „clearly warn humanity of any catastrophic threat.“

„Despite 40 years of global climate negotiations, with few exceptions, we have generally conducted business as usual and have largely failed to address this predicament,“ the group wrote.

In addition to declaring an emergency, the scientists also offered suggestions about the steps that should be taken to address climate change.

„If an individual is concerned about climate change, three things to consider include: one, reducing the use of fossil fuels; two, eating mostly a plant-based diet; and three, having fewer children,“ ecologist William Ripple, the lead author of the warning, told Business Insider.

Greenhouse gases — and Earth’s surface temperature — continue to rise

Steam billowing from the cooling towers of Vattenfall\'s Jaenschwalde brown coal power station is reflected in the water of a lake near Cottbus, eastern Germany December 2, 2009.Reuters/Pawel Kopczynski

The researchers said that in order to properly monitor the climate emergency, it isn’t enough to just track Earth’s temperature change. Population growth, tree loss, meat consumption, and annual economic losses due to extreme weather events are all „profoundly troubling signs“ of how much the climate crisis has escalated since 1979, they said.

So the 40 years of publicly available data on which the analysis is based includes numbers related to energy use, Earth’s surface temperature, population growth, deforestation, polar ice mass, fertility rates, and carbon emissions.

„We are adding voices of scientists from many fields of study to share our findings of the urgency for action and provide multiple milestones for measuring progress in the coming years,“ Ripple said.

Especially disturbing, the authors wrote, are concurrent climate trends in the data: Three abundant greenhouse gases (carbon dioxide, methane, and nitrous oxide) continue to increase along with Earth’s surface temperature.

At the same time, ice is rapidly disappearing from the Greenland and Antarctic ice sheets, glacier thickness is decreasing, and Arctic sea ice is nearly at its minimum. What’s more, ocean temperatures and acidity are increasing, and extreme weather and associated damage costs have been trending upward, they found.

How to address the ‚climate emergency‘: Have less children and eat more plants

The scientists offered a list of strategies that people and governments around the world can use to take immediate action to curb climate change.

Ripple highlighted two solutions that anyone can pursue: „We need to reduce fertility rates through voluntary family planning and depend mostly plant-based diets.“

According to a 2017 study, having one less child is a more effective way of cutting carbon use than recycling, driving an electric car, being vegetarian, or using renewable energy.

„The greatest influence individuals can have in combating climate change is to have one fewer child,“ Ripple said.

Our food system overall — including farming and grazing, transportation, packaging, and feed production — produces 37% of greenhouse-gas emissions, according to an August report from the United Nations‘ Intergovernmental Panel on Climate Change.

To address that problem, the IPCC researchers suggested people eat less red meat.

Cynthia Rosenzweig, a co-author of that report, said that if „almost the whole world became vegan,“ that would prevent the greenhouse-gas equivalent of up to 8 gigatons (16 trillion pounds) of carbon dioxide from entering the atmosphere by 2050.

In this Sept. 12, 2011 photo, Simmental beef cattle feed on hay in a pasture near Middletown, Illinois.Seth Perlman/Associated Press

Carbon pricing and forest restoration could help, too

Besides having fewer kids and eating less meat, the authors of the recent warning also suggest imposing carbon fees on fossil-fuel use, cutting methane emissions, and restoring and protecting natural carbon sinks like forests that sequester carbon dioxide.

Ripple said he strongly supports natural climate solutions, which focus on the conservation and restoration of forests, grasslands, and wetlands, in conjunction with reducing emissions.

But planting new trees and preserving forests aren’t a panacea for climate change; realistically, there isn’t enough space on Earth to plant enough trees to counteract all the carbon humans have put into the atmosphere over the last 250 years. A 2017 paper calculated that the number of trees needed to keep warming below 2 degrees Celsius would cover most land that isn’t forest.

Overall, Ripple and his colleagues weren’t shy about calling for a large, systemic changes in the structure of human society.

According to the researchers, the world should „shift its goals away from the growth of gross domestic product and the pursuit of affluence,“ since „the climate crisis is closely linked to excessive consumption of the wealthy lifestyle.“